Savage-Durable, strong, great support, tons of aftermarket! decent engine not great, decent electronics
MGT 8.0-Durable, strong, great support, not as much afetrmarket but not needed, easiest to work on! Huge 8.0 engine decent not great electronics (I suggest the 8.0 over the 4.6 it has a better transmission you could buy the 4.6 and then get an 8.0 tranny on ebay for $60)
LST-Durable, strong, great support, tons of aftermarket! Best engine of the three, Best electronics of the three

If it's a Monster truck you want any of the three above wont disapoint. If you get it and expect it to be fast not gona happen! If it's fast you want get a truggy or settle on the following! Buy any of the three but go ahead and get either a LRP .28 or .30 or a Picco .28 (the LRP will be the easier of the two to tune but the Picco will blow both the LRP's away) not the only egine options just the most popupar and dependible! Sell the RTR engine on ebay you should get around $120-$160 for it.

Don't expect any of these turcks to be nimble or agile! If thats what you want get a truggy!

My MGT 4.6 tranny didn't hold up to my Picco .28 thats why I suggest the 8.0! Other than that the truck is bulit proof!

Don't expect the Savage tranny or diffs to hold up either some have good luck others bad! I guess thats up to how you drive I don't believe it can handle the strain of that much torque the two speed holds up better that the three!

The LST is probbaly the only one of the three that can handle the LRP & Picco right out of the box!

Since you have been out of it a while and the bug has hit hard take your time! Don't get in a hurry and buy something you will regret! This hobby can get real expensive!!!

Your first serious upgrade will be an engine, pipe then a radio and so on electronics, suspenssion!

Take this serious and take you time! Most of us have at lest $800 - $1,200 invested in a single truck, radio and electronics!

All of those who suggest a truck how about letting us know what you have and how much you have vested in it!

Original MGT .21 bought back in 2003 $375
Clockwerk Picco .28 $275
Ofna 053 pipe $40
Hitec 5955 & 5985 Digital servos $210
FOC $20
8.0 Tranny $80
Mugen MBX6T Shocks $130
Aluminum chassis side plates $20
8MM Axle conversion $100
Dace 23mm hubs $70
($1,320) Total and this doesn't include fuel, glow plugs, batteries, triton 2EQ charger, Futaba radio, and many many extras
For the years of fun I have had and the competitive level it now sits! I'm very happy that it only cost me $165 per year!

Mugen MBX5T $200
Clockwerk Picco .28 $250
Ofna 086 pipe $80
Dace 23mm hubs $70
Hitec 7955 & 5945 Digital servos $210
($810) Total and just to note the MGT will give it a run but the Mugen is just a little to nimble for it!

Good luck with what ever one you chose just chose wisely!